The fluorescence of a single donor–acceptor benzobisoxazole-based cruciform, dissolved in five different solvents, dramatically changes upon exposure to Brønsted and Lewis acids. The changes in emission colors strongly depend on the analyte's structure, and this cruciform can discern among structurally closely related carboxylic (twelve examples) and organoboronic acids (nine examples). In combination with two commercially available phenylboronic acids, this cruciform sensor also distinguishes among substituted phenols (twelve examples).